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-- lua-uni-graphemes.lua
-- Copyright 2020 Marcel Krüger
--
-- This work may be distributed and/or modified under the
-- conditions of the LaTeX Project Public License, either version 1.3
-- of this license or (at your option) any later version.
-- The latest version of this license is in
-- http://www.latex-project.org/lppl.txt
-- and version 1.3 or later is part of all distributions of LaTeX
-- version 2005/12/01 or later.
--
-- This work has the LPPL maintenance status `maintained'.
--
-- The Current Maintainer of this work is Marcel Krüger
local property do
local p = require'lua-uni-parse'
local l = lpeg or require'lpeg'
property = p.parse_file('emoji-data',
l.Cg(p.fields(p.codepoint_range, l.C'Extended_Pictographic')) + p.ignore_line,
p.multiset)
property = p.parse_file('GraphemeBreakProperty', l.Cf(
l.Carg(1)
* (l.Cg(p.fields(p.codepoint_range, l.C(l.R('az', 'AZ', '__')^1))) + p.ignore_line)^0
* -1, p.multiset),
nil,
property)
if not property then
error[[Break Property matching failed]]
end
end
local controls = { CR = true, LF = true, Control = true, }
local precore_lookup = {
Prepend = "PRECORE",
L = "L",
V = "V",
LV = "V",
LVT = "T",
T = "T",
Regional_Indicator = "RI",
Extended_Pictographic = "POST_PICTO",
}
local l_lookup = {
L = "L",
V = "V",
LV = "V",
LVT = "T",
}
local postcore_map = { Extend = true, ZWJ = true, SpacingMark = true, }
local state_map state_map = {
START = function(prop)
if prop == 'CR' then
return 'CR', true
end
if prop == 'LF' or prop == 'Control' then
return 'START', true
end
return state_map.PRECORE(prop), true
end,
PRECORE = function(prop)
if controls[prop] then
return state_map.START(prop)
end
return precore_lookup[prop] or 'POSTCORE'
end,
POSTCORE = function(prop)
if postcore_map[prop] then
return 'POSTCORE'
end
return state_map.START(prop)
end,
RI = function(prop)
if prop == 'Regional_Indicator' then
return 'POSTCORE'
end
return state_map.POSTCORE(prop)
end,
PRE_PICTO = function(prop)
if prop == "Extended_Pictographic" then
return "POST_PICTO"
end
return state_map.POSTCORE(prop)
end,
POST_PICTO = function(prop)
if prop == "Extend" then
return "POST_PICTO"
end
if prop == "ZWJ" then
return "PRE_PICTO"
end
return state_map.POSTCORE(prop)
end,
L = function(prop)
local nextstate = l_lookup[prop]
if nextstate then
return nextstate
end
return state_map.POSTCORE(prop)
end,
V = function(prop)
if prop == 'V' then
return 'V'
end
return state_map.T(prop)
end,
T = function(prop)
if prop == 'T' then
return 'T'
end
return state_map.POSTCORE(prop)
end,
CR = function(prop)
if prop == 'LF' then
return 'START'
else
return state_map.START(prop)
end
end,
}
-- The value of "state" is considered internal and should not be relied upon.
-- Just pass it to the function as is or pass nil. `nil` should only be passed when the passed codepoint starts a new cluster
function read_codepoint(cp, state)
local new_cluster
state, new_cluster = state_map[state or 'START'](property[cp])
return new_cluster, state
end
-- A Lua iterator for strings -- Only reporting the beginning of every grapheme cluster
local function graphemes_start(str)
local nextcode, str, i = utf8.codes(str)
local state = "START"
return function()
local new_cluster, code
repeat
i, code = nextcode(str, i)
if not i then return end
new_cluster, state = read_codepoint(code, state)
until new_cluster
return i, code
end
end
-- A more useful iterator: returns the byterange of the graphemecluster in reverse order followed by a string with te cluster
local function graphemes(str)
local iter = graphemes_start(str)
return function(_, cur)
if cur == #str then return end
local new = iter()
if not new then return #str, cur + 1, str:sub(cur + 1) end
return new - 1, cur + 1, str:sub(cur + 1, new - 1)
end, nil, iter() - 1
end
return {
read_codepoint = read_codepoint,
graphemes_start = graphemes_start,
graphemes = graphemes,
}
--[[
for i, c in graphemes_start'äbcdef' do
print(i, utf8.char(c))
end
for i, j, s in graphemes'Z͑ͫ̓ͪ̂ͫ̽͏̴̙̤̞͉͚̯̞̠͍A̴̵̜̰͔ͫ͗͢L̠ͨͧͩ͘G̴̻͈͍͔̹̑͗̎̅͛́Ǫ̵̹̻̝̳͂̌̌͘!͖̬̰̙̗̿̋ͥͥ̂ͣ̐́́͜͞' do
print(j, i, s)
end
]]
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